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2.6 Conclusion
In the present study, the potential of these 1-substituted 2-hydroxy-2,3-dihydroimidazopyrimidinium
salts and 2N-subsituted 2-amino-1H-imidazoles as inhibitors of
the biofilm formation by S. Typhimurium and P. aeruginosa was thoroughly
investigated. We found that 2-hydroxy-2,3-dihydro-imidazopyrimidinium salts with
intermediate length n-alkyl chains (C7-C10) substituted at the 1-position in general
prevent the biofilm formation of both species at low micromolar concentrations (IC50
= 5-50 µM). For these molecules, the nature of the substituent of the 2-phenyl group
does not have a substantial effect on the biofilm inhibitory activity. Salts with a
shorter (C1-C5) or longer (C11-C14) n-alkyl chain at the 1-position were found to be
much less potent. Consistent with this, we observed that salts with an intermediate
length cyclo-alkyl chain are much more active against biofilm formation of both
species as compared to the salts with a short cyclo-alkyl chain. However, remarkably
salts with a long cyclo-dodecyl side chain were found to have even better activities
than salts with an intermediate length cyclo-alkyl side chain.
In the framework of the 2-aminoimidazoles, be the introduction of a butyl, pentyl or
hexyl side chain at the 2N-position of the 2-aminoimdazoles results in an enhanced
biofilm inhibitory activity against both species, while introduction of a shorter n-alkyl
chain reduces the biofilm inhibitory activity. The effect of introduction of longer nalkyl
chains however seems to be strongly dependent on the substitution pattern of the
5-phenyl ring and the bacterial species studied.
In conclusion, the 2N-substituted 2-aminoimidazoles and 2-hydroxy-2-phenyl-2,3dihydro-imidazopyrimidinium
salts of the present study are valuable candidates in the
development of therapeutics and sanitizers for the combat of biofilm formation by S.
Typhimurium, P. aeruginosa and possibly other pathogenic bacteria.